The new Vacheron Constantin Les Cabinotiers 'La Musique du Temps' Astronomical Striking Grand Complication is an ode to music and provides a fresh demonstration of Vacheron Constantin's technical mastery in the creation of horological grand complications. As part of the range of exceptional chiming watches named "La Musique du Temps", this new one-of-a-kind creation is based first and foremost on a minute repeater which determined the construction of the entire movement. The starting point for the work was the famous in-house calibre 1731, due to its extreme thinness. Redesigned to accommodate a range of astronomical functions, the new calibre 1731 M820 is thus equipped with 19 complications. This unique double-sided minute repeater displays solar, sidereal, and civil time complete with a perpetual calendar.

Born from the need to tell the time in the dark in an age when people had to rely on candlelight, chiming watches have taken various forms: repeating on demand the hours, quarters or half- quarters, as well as the minutes depending on the versions; Grande and Petite Sonnerie —sounding the hours and quarters in passing, with or without repeating the hour on each quarter—; and finally those with an alarm —programmable chime. While each of these complications has its own distinctive characteristics, they all combine an integrated and complex mechanism with the finely crafted nature of musical instruments in terms of their resonance, acoustics, and harmonics. Featuring watch cases equipped with complex movements as their only means of musical expression, these creations represent a magnificent feat of miniaturization.

At Vacheron Constantin, the first mention of a chiming watch dates back to 1806: a gold repeater pocket watch registered by the founder’s grandson Jacques Barthélemi Vacheron, in the very first production register kept in the company’s archives. Ever since, sonnerie or repeater watches have been an integral part of the Manufacture’s proud heritage, steadily enriched over the decades.

The starting point was the famous in-house 1731 movement, due to its extreme slimness for a minute repeater mechanism. At just 3.90 mm thick, the calibre 1731 also has an impressive 60-hour power reserve and a magnificent sound quality, thanks in particular to the development of an entirely silent flying strike governor. This movement has therefore been reworked to accommodate the astronomical complications that make this timepiece an exceptional watch. With the new calibre 1731 M820, the es Cabinotiers 'La Musique du Temps' Astronomical Striking Grand Complication is thus equipped with 19 complications housed in a space barely 7.84 millimeters thick.

The Indications

This watch is equipped with a perpetual calendar that is harmoniously expressed on the blue opaline dial. The date is indicated by a serpentine hand in a snailed counter at 3 o'clock for the sake of legibility. The days, months, and leap years are discreetly displayed in windows between 12 and 2 o'clock. The date is indicated by the precision moon phases and age, but also the day/night indication which is coaxial to the moon phases, a logical and lyrical complement to the perpetual calendar. The lower part of the dial is occupied by the pointer-type display of sunrise and sunset times, complemented by a linear indication of the length of day and night. A 4 o'clock aperture also reveals a disc bearing the signs of the zodiac, seasons, solstices, and equinoxes.

As heralded by the latter functions, this piece is first and foremost an astronomical watch which, in addition to the civil time indicated by the two central hands, also displays the particularities of solar time. Since the Earth's path around the Sun describes a trajectory that is not circular but instead elliptical, and given that the Earth's axis is inclined at 24-degree to the plane of its orbit, the time between two solar zenith passages is not the same throughout the year. This difference between the solar —true— day and the civil —average/mean— 24-hour day ranges from -16 to +14 minutes depending on the time of the year, coinciding only four times in 12 months.

Known as the equation of time, or time correction in astronomical parlance, this information has long fascinated watchmakers. The fact that these variations are rigorously identical from one year to the next makes it possible to program them mechanically via an annual cam that controls the display of this time differential. For this timepiece, the company's master watchmakers have chosen the rarer and more complex solution of a running equation of time. This consists of also displaying solar time by means of a central minutes hand, in this instance symbolically serrated, and thus enables instantaneous reading of both civil and solar time.

An astronomical watch according to Vacheron Constantin's master watchmakers would not deserve its name without an indication of sidereal time. This is precisely what can be viewed on the back of this timepiece, with a sky chart ingeniously formed by two superimposed sapphire discs. Taking a fixed star in the sky as a reference point, the time it takes the Earth to complete a full 360-degree revolution, or sidereal day, is exactly 23 hours, 56 minutes and 4 seconds. Since the Earth both spins on its axis and revolves around the sun, it takes about four minutes less than a calendar day to return to its point of departure in relation to the given star. In this model, the first lower mobile disc is rimmed by a sidereal time scale punctuated by the cardinal points, which thus rotates in step with sidereal time.

Still, on the same disc, an off-centered blue ellipse serves as a transparent indicator of the constellations of the celestial vault, which are positioned on the fixed upper disc. This mechanical ballet thus reveals the vision of the sky in motion as seen from a given point on Earth. This same second disc also bears a white ellipse for the celestial equator and a red ellipse for the ecliptic. While the first is a projection of the equator onto the celestial sphere that takes into account the Earth's approximately 24-degree inclination, the second represents —from a heliocentric point of view— the plane of the Earth's orbit serving as a reference for celestial coordinates. Finally, one notes an intense blue dial bearing the months of the year.

The difference between the sidereal day and the mean or average day means that the movable lower disc will accelerate daily by some four minutes in relation to the fixed outer disc, so as to indicate the current month at exactly midnight by means of a yellow arrow.

Housed in an 18K pink gold case measuring 45 mm in diameter and barely 12.54 mm thick, perfectly designed to accommodate the sky chart corrector and the minute repeater slide on the case middle, this calibre is one of the very few movements to offer simultaneously a minutes repeater and the civil, solar and sidereal time. This extreme level of complexity is matched by the exceptional finishing of this timepiece, including the Côtes de Genève that can be admired through the transparency of a movement that appears to be floating in the stars. A midnight blue alligator leather strap with pin buckle rounds off the elegance of this captivatingly complex timepiece.

As partners of the Maison, Abbey Road Studios have recorded an original sound print delivered as a one-off certificate for each of the pieces in the range dedicated to ‘La Musique du Temps.’

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Technical Specs

Reference: 6620C/000R-B656

Movement: In-house Calibre 1731 M820, Manual-Wound, 600 parts, and 36 jewels. Power reserve of 60 hours.

Case: 45 mm in diameter x 12.54 mm thick in 18K 5N pink gold.

Case Back: Display with Sapphire Crystal and water-resistant tested to 50 meters.

Front Dial: Blue Opaline dial with Hours, minutes, Minute repeater —hours, quarters and minutes on demand—, Perpetual Calendar —the day of the week, date, months and leap year—, Running equation of time, Precision moon phases, Age of the moon, Day/Night indication, Sunrise/Sunset indication, Day/Night length indication, Tropic and zodiac disc —seasons, equinox, solstices and zodiac signs.

Back Dial: Celestial hours and minutes, Transparent sky chart of the northern hemisphere with an indication of the Milky Way, of the ecliptic and celestial equator.

Strap: Blue Mississippiensis alligator leather with alligator leather inner shell, hand-stitched, saddle-finish, large square scales, and secured by an 18K 5N pink gold folding clasp. Also, delivered with an additional 18K 5N pink gold polished buckle with a half Maltese cross.